Utilization of same next hop when not expected

[patchesgarcia]

Using figure 8 (HDTN Four Nodes STCP Routing test) from the user guide as reference.

The desired setup is to have node 4 act as a final destination sink. Node 1 will send data to its final destination using node 3 as a router. In parallel we would also like to have another source node (node 5) use node 2 as a router to send data to node 4. Two independent data pipelines sending data to the same final destination, node 4.

The above can be done without issue. However, once we add an additional next hop to one of the source nodes both source nodes use the same next hop. This is not expected behavior and the hope was to continue to replicate the two parallel independent pipelines as previously described. For example holding all else true, if node 1's HDTN config file has node 2 simply added to it then the end result will have both node 1 and 5 use node 2 as the router. We would like this behavior only after manipulating node 3 to become unavailable so as to allow the router to update optimal path choice based on link status.

Can what is being described be done? We are using TCPCL and the default routing algorithm which I believe is Dijkstra's algorithm according to the README. When we add the next hop the corresponding contact is created in the contact plan with similar settings so as to not skew one contact being favored over another.